Surface attached fluorescent lighting luminaire



June 28, 1949. v; s. wlNcE 2,474,341

- SURFACE ATTACHED FLUORESCENT LIGHTING IIUMINAIRE Filed Nov. 29, 194ePwr- F1 7 /z lNyENToR Mmm, S W//vc'e lPatented June 28,1949

SURFACE yATTACHED A'FLUoREsoEN'r LIGHTING LUMINAIRE VearlS. vWince,lNewark, OhioLassignoivv to Ho10 phane Company, lne., New-York, N. Y.,alcorporation- .of Delaware Application Novemberv` 29, 1946; Serial No;713,125?.

13A .Clainis.y

TheA presenttinventiorr relates f to'vsurface at tached; iiuorescen-t:lighting; luminaires, andi is. more particularlydireeted towardtota'llyen-closed luminaires `using-:long lightsourcesgand arranged for bothdirect and-indirect.lighting:

It has heretofore;y .beerr customaryv to employ4lenseszbelowxfluorescent lampsitocontrolthe dis,- tribution of lightinfplanesltransverse oftlrielamps4` and to; employ? metal .or" porcelaina enameled or,

pear as the description proceeds.

' The accompanyinggdraWings-showg for purposes of; illustrating; thepresent-invention; an embodimentzimwhickthe inventionufrnayf take:fform', together wthmodications-of;certain-parts, itbeingf understoodtha-ti thedrawingslare, illustrative of thenvention rather-than limitingvthe saine In-:theseldrawingsf:

Figure 1 isqavperspectiveviewdiagrammatically illustrating theluminaire;

Eig-ure. 2,fis arftransversez-sectional view showing typical ray, paths;

l'igui-esv 3 and 3a; arei fragmentary transverse sectional views;through -one vform of top, reflector;

painted reflectorsaboutthelampsitozdirect upfv 10 Figure'zl-isiaffragmentarytransverse sectional wardly emitted light generallydownwardli'f,` onto. View. of the 2 typical: priore art:.tota1ly=.reflectingthe; lenses.: When;- such: luminaires' are Aviewed prism;

froml lateral kpositionsfloelovvi` the:v lenses the con- Figurer 5 .is-las iragmentary;transverse L,sectional trast-,in-=brightness odi thef-near and remote side View" through -animproved :form .of totallyreflectof-fthe lensesfpisgcomparatively low; fortheglight 15ingfprism';l

scattered ahoutf-insidethe reilectorv falls lony the Figure 6-iszadiagrammatic inverted plan View remote side-:of r tlie1enses:at:anglesf:whichl permit Off the luminaire;

thef lenseszto sendtsomeg-light:across the longitu+ Figure 'Lisaphotometricchartillustrating-disdinal vertical mediarrplanethroughthefluminaire. tribution of :lightiaCIOSSvthe luminaire.;

Such; luminaires:howevenzwereunsuited: forl 2i) Egurefnisasirnilarfchart illustratingfdstis obtaining. an upwardrcomponent'oflight; Where bution of-light lengthwise 0f '011elumnaire@mdf an f indirect: lightingf component? ist desired,n from Figure 29;iSva View Similar' IJOrFgllle 3'11111Si71aI3- totallyenclosedlightingrxturesfthe employment ing .fa-modied form oflreflector:on@V lightv transmitting:elementsgpfaglasslorother IH the presen-tb'llllltiolfellles` 0f the' 111eV light transmittingmediumaloove:v and.lateral of 25 mil-arefOtheI than 115116;lightconmllingieatures; thelamps irmlicaxgd, Not-faugforms of 17h-@Same are omitted-:Aisuitablerform loffconstruction Afor are; Suitable for; thepuTpOSebecauseA ztheyma yn r supportingtheelightfcontrolling .parts is shown intraduce' undesired brightness; on theirr surfaces f"pp1mat.i0n"frpatemfor Surface attached light" andmayvredce thelightidirectedionto theslower mgfeqm'p-mentf Ser1a'1 N0' 7'13126f1ed byKQurtplatesneeded@maintain ,them at desired. Hover 30 Eranck-andVearlS.,.W1nce, oneven date herewith. brightness.. The b odyfofthefixtureissindicatediat IU'. It According to'thepresent inventiontlie'lumi` Supp0rt`-uorescentlampsiindcatd:at!l lower naires areprovided' Withlighttransmitters in the pnsnilatlc pltes '2f andupp-rprlsma'tw" mates form: of vprismatic reflectors which.; emitan up '.3*3' Thef'lowr16959124654adlrectthe dlrectwardcomponentofiilluminationat"higherangles 35 11ght"'toward'thnadmas*mdlcatedibylthe rays l Y d1rect.-l1g-htfabovetheplanethrough'the-bottomof them, and the light theyrefiectdownwardlyism theflampsanduptoanfangle'offa'boutllS-abovesuch.controlleddlrections as ,to fall on the lower lens plates at angleswhich permit' transmission the-s1de`1amps- Some'oflthlshght 1s below'the across-A the lumnaie 40 horizontal and -iflits-adirectionaverenotfclfianged,

Th t. l t t ill-Would; proceed slightlyv Iuelow'lv the horizontal ne tamg@ lonffasll Congmf a esprlsma 1C I' causing comparatively.brightaconditionsi- To rec Ors* avmgffo a Y* Ife ec' 1ngf`=PnSms- Cap-ae directe1 this-light?.inmoref-useful directions, the@fitotauyfreflectmg-hght :Convrgmg-Poward-the plates I3 are providedvwithvertical, totallyrep rlsmsat vvide. ang1es..to,the1r med1an planes-45 iiectingu-external prisms'Ifandlareeprovided with Thus: the, obliqueraysarereflected so asfto produce a?. pfsmac` prolewmchv, may ,appeareither on 'S14 more2' even f-hgzhtedf am?mmel pattern 0nthe' thelinsideoi`v the reflectors-fl 3 as shown iny Figures lowenflensesfthrough`aiwide: lateral rangeiofzobf 2I 3 amiga, asmdcatedahl1; @non theoutsideServatlon offthereflectorsfas:shown in Figure 9:

other and furtherob'letswill heemafteffap- 50 As showniniFigures-zyandz.Sa'ftransversefof the lamps,direotf1ight 'raysffsuchas I I 9;v 20,1- 2.1; 2,2,l 23, 24;- fa-ll on- .the inner surface-ofthereectors l 3; Where'ftheslongi-tudinaleprismaticzridges are onthelinsidezof Ithe reflectors andupwardly thick eningv; asindicatedv-inlligures5253 and 3a, theirays are retracted upwardly, asindicated by the typical rays I9 and 24, and fall on the the totallyreflecting prisms I6 making up the outer surface of the reflector I3. Aportion of these rays is transmitted through the transparent medium,typically glass, and these rays have the same vertical angle as theywould have if the outside surface were smooth. Such transmitted rays areindicated at |817, |91) and 20h, 24h. These rays are at a higher angleabove the horizontal H than the corresponding rays I8, I9, and 24 owingto the refraction occurring at the incident surface having the prismsil.

The dominant portion of the light in the rays I9a and 24a, typical raysin the glass, is, however, reflected by the totally reflecting prisms,back into the glass as indicated at |90, 24o. These rays pass throughthe refracting prisms I1 and enter the space inside the luminaire withcomparatively steep vertical angles such as indicated at |801, |9d, 29d,and 24d and fall on the lower glass plate l2 at comparatively steepangles. They are refracted by the prisms of this plate across thevertical axis XX of the luminaire so that an observer looking at theluminaire from a suitable distance below the luminaire and in thedirection indicated by the arrow A (Figure 2) will receive considerablelight from the left or opposite side of the bottom plates of theluminaire.

This effect is much more pronounced than would be the case if the upperplate |3 were a diffuser or were a prismatic reflector in which theprofiles of the inner and outer surfaces were parallel. To illustratethe deviation caused by the prisms as compared with the direction such aray as I9 or 24 would take if there were no prisms l1, Figures 3 and 3ashow in dotted lines such a light ray at I9', I9", |9'", and 24', 24",24"'. In the absence of refracting prisms such as l1, the transmittedlight would have the same vertical angle as the direct light, and towardthe bottom of the reflector much of it would be below the horizontal H,providing high brightness in that region. As the reflected rays I9 and24" are considerably nearer nadir inside the luminaire,

they would not tend to provide brightness on the side of the luminaireremote from the observerA If the light rays to be controlled were all inthe transverse planes of the luminaire, the outer prisms I6 could takethe usual form of a 90 totally reflecting prism such as indicated at 25in Figure 4. Such a prism would accept an incident ray such as 26 andreturn it as indicated at 21 parallel to itself but in different planescorresponding with the Obliquity of the ray 26 to the incident surface.Such 90 angle prisms, however, are suitable only when the incident raysare nearly parallel to the plane 28--28 of symmetry of such 90 prisms.`For example, light rays such as 29, 29' strike the surface of the 90prism at angles such as to escape as indicated at 29u. and 29a',respectively. Owing to the length of the fluorescent lamp, much of thelight falling on any elemental area of the reflector I3 comes fromremote areas on the lamp and hence has substantial angles of incidencemeasured in longitudinal planes and, therefore, cannot be handled byconventional 90 totally reflecting prisms,

Figure 5 illustrates an improved form of totally reflecting prism I6adapted to totally reflect light rays converging toward the areaopposite the prism from points on the lamps distant from the medianplane 30-30 of the prism. Rays converging through an angle toward theprisms so as to have angles of incidence up to 45 are indicated by rays3|, 32, 33, 34. Rays such as 3| near the axial plane strike the outersurface near the apex of the prism where it has an angle of 90 and arereturned as indicated at 3| in directions parallel with the axial plane.The sides of the prism I6, however, do not have the 90 relation, exceptclose to the apex. The sides of the prisms are concaved as indicated inFigure 5 so that the refracted rays 32a, 33a, 34a, corresponding withrays 32, 33 and 34, strike the sloping sides of the reflecting prism I6at such angles as to be reflected across the prism parallel with theentering face. These reflected rays are indicated at 32h, 33h and 34D.They strike the opposite face of the prism at angles suitable for totalreiiection and are returned toward the incident face as indicated at32e, 33e and 34o, and are transmitted through the inner surface of thereflector as indicated at 32d, 33d and 34d. The light reected back intothe luminaire thus diverges from the plane 3|l39 to the same extent thatthe entering light converged. The light received by an elemental area ofthe reflector from the lamp to one side of the plane 30-30 through thisarea, is, therefore, transmitted back into the luminaire the other sideof the plane Sli- 30, and it is therefore apparent that the reflectorsare such as to accept light travelling in oblique directions withrespect to the length of the luminaire and reflect this light incorresponding oblique directions.

The action of the prisms illustrated in Figure 5 is diagrammaticallyillustrated in Figure 6 where the luminaire is illustrated fromunderneath. Any point such as Y on the lower surface of the plate l2 onthe side remote from the observer receives reflected light fromdirections up to each side of the transverse plane through the luminaireand the lower plates transmit this light with altered vertical angledepending upon the prismatic configuration of the lower plate butwithout affecting its spread away from the transverse plane. Thus, fromsuch point Y one obtains divergent light rays between lines such as 34',34", corresponding in direction with the rays 34-34d. Thus the entirelower surface of the plates l2 transmits in addition to the dominantdownward light rays |4a, |5a, additional light rays such as |8e, |9e,20e, which cross the luminaire axis and have wide divergence from thetransverse plane as indicated by the rays 34', 34". This brings aboutbrightness of the remote side of the luminaire which is much higher thanwould have been the case were less efcient forms of reflector employed.This increase in brightness occurs over comparatively long areas of theluminaire when the luminaire is viewed at angles within 45 from thetransverse plane.

The over all result of the prismatic constructions described above, isillustrated in the photometric curves 40 and 4| of Figures 7 and 8,respectively. The curve 40 shows the light distribution in transverseplanes and indicates that there is a substantial light outputconcentrated in the general direction of about 15 above the horizontal.This light is very effective in obtaining upward illuminationparticularly of a ceiling at or close to the top of the body I0 of theluminaire. Owing to the upward direction of the light, the brightness ofthe reflectors |3, while substantial, is comparatively low.

In the modification of the reflector illustrated in Figure 9, the innersurface of the reflector has a smooth profile and the outer surface hasvertical prisms 50', stepped as indicated. Inci- @wenn dentt raysfsuchas.-` 51, corresponding-.in positionr with ray: 24, are refracted on`entering f. the. rea'. fle'zctor` and directed .toward ithefy outer isurfacesiasr.v indlcatedat 52." These rays'lare in part reflected? asindicated.: at 5351 and refractively: transmitted; as shown at 54, andin part transmitt'edfas-.iindie.- cated at 55; Theaction'isfsi-milartoethat of Figures-S- and 3a'. Theconstruction:withi-smoothi outer prole is .preferableewhere fixturedesigniindicates .a steepprolewhile.: the inner?smooth; profilesuitableffor designs 'where theffpro-le ist flatter. e

Since it is obvious that the-inventionmayrbezi embodied :in f otherforms-.and constructions .wither in' the .scope of ftheffelaims, I!wish'.itatobeunderm stood that vthe l particular: form shownA isfzbutf4one;D of r. theseforms, and.r various modificationsl andi changesAbeing. possible, I doinototherwise'llimit: myself 'in any -waylwi'tl'il`respect"thereto.I.

What is claimedis:

1;. A fluorescent lighting. luminaire; havingff a horizontal.rectilinear. fluorescent-z lamp, and* a; reflector parallel with.thelampt-andoccu-pying zone off'subst'antial angular:widtheextending'zups:

wardly from substantially theilevel offtherbottomse ofthe lamp so astointercept' lowen"angledfups` wardly directed light, the reflectorhaving;az'pres4 determined generali profile having a series of external,vertical, totally reflecting prisms crossed by a series of upwardlythickening'horizontal refracting prisms forming-a.r stepped profileonone surface, the series of refracting prisms cooper-'- ating toelevate both the transmitted light emitted through the upper surface andthe-reflected light emitted through the lower' surface as comparedswithnthe directions obtainable .with-fa reilectorz'of likeprole smoothboth inside andout.

2. A fluorescent lighting luminaire as claimed in claim 1, wherein thestepped profile is on the inner surface.

3. A fluorescent lighting luminaire as claimed in claim 1, wherein thestepped profile is on the outer surface.

4. A fluorescent lighting luminaire comprising the combination with ahorizontal light source, and a refractor intercepting downwardly emittedlight and having longitudinal prisms each thickening toward thelongitudinal median plane and which deviate direct light toward nadir sothat more light is transmitted from the near side of the luminairetoward an observer lateral of and below the luminaire than from theremote side whereby the near side is brighter at such angles ofobservation than the remote side, of

means for building up the brightness of the remote side of the fixturecomprising a downwardly and outwardly flaring, externally verticallyribbed, prismatic, light reflecting cover intercepting low angle lightabove the horizontal and having internal longitudinal refracting prismson one of its surfaces each thickening toward the longitudinal medianplane and which act to elevate the reflected light transmitted throughits lower surface so that it is directed toward the refractor at greaterangles from the nadir than by a transversely smooth surfaced reflectorof the same general profile.

5. An elongated luminaire having a rectilinear fluorescent lamp, arectilinear light concentrating lens below the lamp with regressed lightconcentrating prisms for deviating direct light toward the nadir wherebythe side of the lens nearer a. laterally positioned observer below theluminaire directs substantially more of the direct light toward theobserver than the remote side 64; ofthe lens;y andinternelly?.concavespecular; pris-1i matie- -reflectorsf` above-fthe` sides the` lens lin#at position toacceptlowzangledirectfliglit-above the; horizontalI andhavingflongitudinal refracting f prisms each thickeningiftowardl thelongitudinali 1 J 51,-wherein thefreflector hasexternal,-y verticalisymmetrical; total-ly reflecting# prismsl with sides-fat an angle of``atl1the-apexfand atincreas'`` ing angle remote fromftheap'ex.`r

7. The combinationlwith' a f. horizontal clon i gated light'source of aprismatic reilc'ect'or` par.L

allel with the liglfit'source,y the.reflectonh'ayi'rrgrw series ofrelatively` small totally reflectingpris-ms.I extending verticallylon'rits'iouter. surf ace, the sides.. ofthe prisms being lat .45 tothemedian:plane".v

` throughthe prisms atl` the apex' ofi the prismsrso as to totallyreflectflightlsubstantially normal! to the inner surface; oppositek theprism'V and at.E increasing angles remote from the ape-x sonas itortotally. reflecty light converging toward the `prism.;

8. A luminaire having: an '.elongated horizontan light.. source," arefratstorr` under# the. light. sources having regressed light:concentratingl prisms;y which deviate the ldirezctzlight` receivedthereby; toward thenadir, andsupper. reiiectors laterally of. the sourceand=abovefezthe lower..-'refractor, the: upper reiiectors having, a`series Hof-external, ver-VL tical, totally reflecting prisms,- ,crossedby., aseriesg. of internally disposed upwardly thickening, horizontalrefracting prisms which increase the angle of incidence of direct lightand the angle of refraction at the entering surface, decrease the angleof incidence and reflection at the outer surface and decrease the angleof incidence and of refraction of reflected light at the emergentsurface and direct this light onto the lower refractor at higher anglesthan a reflector ofthe same general profile and smooth inner surface.

9. The `combination with a horizontal fluorescent lamp of a reflectorconcave toward the source and extending upwardly and inwardly from aregion substantially level with the bottom of the lamp to intercept lowangle light above the horizontal, the reflector being composed oftransparent light transmitting material and having a smooth profiledouter surface composed of adjacent totally reflecting vertical ridgesand an inner surface composed of longitudinally extending refractingridges with incident faces less steep than the opposed outside prolewhereby increased upward deviation of the light rays is obtained at therst refraction on entering the reector and" decreased downward deviationat the second refraction on leaving the reflector.

10. The combination with a rectilinear light source of a reflector madeof a transparent light transmitting medium extending parallel with thesource disposed to intercept a wedge of direct light from the source andhaving an inwardly concave, non-concentric profile, the reector having aseries of external, vertical, totally reecting prisms crossed by aseries of upwardly thickening horizontal refracting prisms forming astepped profile on one surface, the series of refracting prismscooperating to elevate both the transmitted light emitted through theupper sur face and the reflected light emitted through the lower surfaceas compa-red with the directions obtainable with a reflector of likeprofile smooth both inside and out, each side of each reflecting prismbeing inwardly convex and disposed at variant angles to the refractedrays in the rnedium greater than the critical angle of the medium toproduce total reflection and such as to reflect the convergent raysincident thereon in directions parallel with the light incident face andtoward the opposite side of the prism for total reflection therebytoward the light incident face with divergence corresponding with theirconvergence before the first reflection and for refractive transmissionon the other side of the normal plane with divergence corresponding withthe convergence of the original ray.

11. A reflector made of a transparent light transmitting medium andhaving a rectilinear light incident face adapted to receive light raysconverging on elemental surfaces thereof from an elongated sourceparallel with the light ineident face, and extending both sides of theplane normal to the said surface at said surface and to refractivelydeviate and transmit said converging rays toward the opposite face withdecreased angles of convergence, the opposite face being in the form ofa symmetrical reflecting prism extending in the direction of said normalplane, each side of each reflecting prism being inwardly convex anddisposed at variant angles to the refracted rays in the medium greaterthan the critical angle of the medium to produce total reflection andsuch as to reflect the convergent rays incident thereon in directionsparallel with the light incident face and toward the opposite side ofthe prism for total reflection thereby toward the light incident facewith divergence corresponding with their convergence before the flrstreflection and for refractive transmission on the other side of thenormal plane with divergence corresponding with the convergence of theoriginal ray.

l2. A prismatic reflector for use with a normally horizontal long lightsource, the reflector having external vertical symmetrical ribs withtheir sides at an angle of 90 near the apex and at increasing anglesremote from the apex.

13, The combination with a horizontal fluorescent light source of lighttransmitting reflectors on each side of the source, of inwardly concaveprole which intercept direct light at low angles above the horizontal atsubstantial angles of incidence and have externally disposed verticalreecting prisms which reflect a substantial portion of the lightdownwardly and inwardly toward the nadir and allow a portion of thelight to escape outwardly, and wherein one of the surfaces of thereflector has longitudinally extending refracting prisms each thickeningtoward the longitudinal median plane and elevating the light in itspassage through the reector so that the escaping light is at higherangles than the corresponding direct light.

VEARL S. WINCE.

REFERENCES CITED 'Ille following references are of record in the le ofthis patent:

UNXTED STATES PATENTS Number Name Date 1,799,290 English Apr. 7, 19312,281,377 Ohm Apr. 28, 1942

